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. 1982 Jan;79(1):51–55. doi: 10.1073/pnas.79.1.51

In vivo regulation of rat liver 3-hydroxy-3-methylglutaryl-coenzyme A reductase: immunotitration of the enzyme after short-term mevalonate or cholesterol feeding.

R E Arebalo, C D Tormanen, J E Hardgrave, B J Noland, T J Scallen
PMCID: PMC345659  PMID: 6948302

Abstract

In recent studies using either a single dose of mevalonolactone administered by intragastric tube or a single meal containing 2% cholesterol, it was demonstrated that rat liver hydroxymethylglutaryl-coenzyme A reductase [mevalonate: NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34] (HMG-CoA reductase) the major regulatory enzyme in cholesterol biosynthesis, is subject to two phases of inhibition. The first phase of inhibition is explained by in vivo phosphorylation of the enzyme; however, the nature of the second phase of inhibition remained obscure. The present study tested two possible explanations for this second phase of inhibition--increased enzyme turnover leading to a decreased concentration of HMG-CoA reductase molecules, and further inactivation of existing enzyme molecules. The results with the technique of immunotitration of HMG-CoA reductase show that, in short-term studies conducted up to 2 hr after the administration of a single dose of mevalonolactone or up to 6 hr after a single meal of rat chow containing 2% cholesterol, the in vivo regulation of rat liver HMG-CoA reductase during the first half of the dark period does not occur by increased enzyme turnover but, instead, existing enzyme is further inactivated.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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